Apparatus for bending metal tubing



Aug. 13, 1968 L. c. MILLER APPARATUS FOR BENDING METAL TUBING 2 Sheets-Sheet 1 Filed Sept. 30. 1965 INVENTOR.

L. C. MILLER APPARATUS FOR BENDING METAL TUBING Aug. 13, 1968 2 Sheets-Sheet 2 Filed Sept. 30. 1965 INVENTOR. BY 5 Q l E (av/W245 63/14/4466 United States Patent 3,396,565 APPARATUS FOR BENDING METAL TUBING Leonidas C. Miller, L. C. Miller 01., 717 Monterey Pass Road, Monterey Park, Calif. 91754 Filed Sept. 30, 1965, Ser. No. 491,621 3 Claims. (Cl. 72216) ABSTRACT OF THE DISCLOSURE Clamp mechanism for intermittently advancing a tubing axially through a bending frame assembly includes a first clamp device fixed on .a stationary frame and a second clamp device reciprocable on the frame, the second clamp device having jaws which float vertically for selfpositioning with respect to the tubing.

This invention relates to metal forming apparatus and is particularly directed to a machine for bending metal tubing or pipe and particularly electrical conduit.

This invention relates to improvements over the apparatus disclosed in the Bright Patent 3,075,568 granted Jan. 29, 1963. In that patent there is disclosed apparatus for advancing conduit by intermittent motion through a conventional three-point bending frame assembly. The conduit advancing device comprises a single clamp which engages the conduit and which is advanced longitudinally along the base. The conduit is not released from the clamp until all of the bending has been accomplished. This construction requires a very long base and is primarily useful only for producing completed bends having substantially constant radius.

It is an important object of the present invention to provide bending apparatus of the general type shown in the Bright patent but having a novel form of feeding mechanism for moving the conduit intermittently through the bending device, so that the overall length of the machine may be greatly shortened and so that bends having variable radius (for example, an involue curve) may be produced.

Another object is to provide a device which may be operated with considerable precision by relatively unskilled personnel.

Briefiy stated, these and other objects of the invention are achieved by employing a pair of novel clamping devices for engaging the conduit; one is fixed against longitudinal movement on the base and the other is mounted to reciprocate under power with a relatively short stroke longitudinally on the base. Means are provided for alternately closing and opening the stationary clamp and the moving clamp so that the conduit is advanced toward the bending frame assembly in step-by-step increments. Also, adjustable means are provided for varying the stroke of the moving clamp device.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings, FIGURE 1 is a side elevation of a machine comprising a preferred embodiment of this invention.

FIGURE 2 is a plan view thereof.

FIGURE 3 is a sectional elevation taken substantially on the lines 3-3 as shown on FIGURE 2.

FIGURES 4 and 5 are transverse sectional elevations taken substantially on the lines 44 and 5- 5, respectively, as shown on FIGURE 3.

FIGURE 6 is a sectional detail taken substantially on the lines 6-6 as shown on FIGURE 3.

FIGURE 7 is a sectional detail taken substantially on the lines 7-7 as shown on FIGURE 1.

FIGURE 8 shows a portion of FIGURE 3 and illus- 3,396,565 Patented Aug. 13, 1968 trates the action of the bending frame assembly and the clinometer.

Referring to the drawings, the frame or base generally designated 10 may be supported on wheels 11 and 12 for mobility. A conventional three-point bending frame assembly 13 is pivotally mounted on the upper portion of the base 10 near one end thereof. This bending frame assembly comprises a pair of longitudinally extending, laterally spaced parallel side plates 14 and 15. The plates are maintained in alignment by cross bars 16. A horizontal pivot pin 17 projects laterally through aligned aperutres 18 on the parallel plates 19 and the pivot pin also extends through aligned apertures provided on the side plates 14 and 15. Several aligned sets of apertures are provided on the bending frame side plates and also on the plates 19 which are fixed to the base 10, for use in bending conduit of different sizes.

A second pin 20 parallel to pivot pin 17 extends through aligned apertures 21 provided on the bending frame side plates 14 and 15, and the projecting ends of this horizontal pin 20 rest on horizontal support surfaces 22 provided on the stationary plates 19.

A metal tube or conduit 24 extensd longitudinally through the bending frame assembly 13 between the side plates 14 and 15. This conduit 24 rests on contact blocks 25 and 26 which are piovtally mounted on the pins 17 and 20 between the side plates 14 and 15. These blocks 25 and 26 have curved surfaces which conform to the curvature of the outer surface of the conduit 24. A power cylinder assembly 27, hydraulically operated, is fixed to the side plates 14 and 15 in a central position and has a downward projecting piston rod 28 carrying a bending shoe 29 on its lower end. This shoe 29 has a curved surface shaped for contact with the conduit 24. When hydraulic fiuid under pressure is admitted into the assembly 27, the piston rod 28 is extended and the shoe 29 applies lateral pressure to the conduit 24 in a location midway between the contact blocks 25 and 26. This produces a bend in the pipe.

In accordance with this invention, novel means are provided for advancing the conduit 24 in step-by-step relation through the bending frame assembly 13. A first clamp device generally designated 32 is mounted on the frame 10 and held against longitudinal movement. A second clamp device generally designated 33 is mounted for longitudinal reciprocation with respect to the frame 10. The first clamp device 32 has a pair of spaced lower jaws 34 attached to straps 35 fixed to the frame 10. A vertically movable upper jaw 36 is fixed at any one of a series of positions on parallel vertical bars 37 joined at their lower ends by a cross bar 38. A hydraulic cylinder assembly 39 is fixed with respect to the lower jaws 34 and has a projecting piston rod 40 connected to the cross bar 38, so that the cross bar and consequently the upper jaw 36 may be raised and lowered under power. The jaws 36 and 34 are provided with V-shaped grooves 41 for gripping the conduit 24 therebetween. The vertical bars 37 slide between the stationary jaws 34.

The clamp device 33 includes a pair of cross heads 43 which slide on parallel longitudinal slide bars 44 fixed to the stationary jaws 34. Parallel vertical bars 45 carrying upper jaw 46 are moved vertically by means of the power cylinder assembly 47, piston rod 48 and cross bar 49. The lower jaw 50 is mounted to slide vertically within the cross heads 43 and the jaws 46 and 50 have V-grooves for contact with the outer surface of the conduit 24. The jaws 46 and 59 are floating in the sense that their final position when clamped is determined by the height of the conduit 24 which they clamp between them. This is to be distinguished from the construction of the clamp device 32 wherein the lower jaws 34 are fixed relative to the frame 10 and hence no floating action is provided.

A stationary transverse bar 51 fixed to the base 10 is connected to horizontal piston rods 52. These piston rods 52 are connected to pistons 53 within parallel power cylinder assemblies 54. The outer cylinder of each assembly is connected to the cross heads 43. These parallel power cylinder assemblies 54 serve to reciprocate the clamp device 33 along the parallel slide bars 44, by admitting and exhausting hydraulic fluid from opposite ends of the cylinders.

Suitable pumps, conduits and valves are provided for carrying hydraulic fluid to and from the opposite ends of power cylinders 39, 47 and 54. The power cylinder 27 on the bending frame assembly 13 has a single hydraulic connection 30 for delivering hydraulic fluid to depress the piston rod 28 and shoe 29; the return motion is accomplished by an internal spring, not shown.

Means are provided for limiting the stroke of longitudinal travel of the clamp device 33 along the stationary slide bars 44. As shown in the drawings, and particularly FIGURE 7 thereof, a microswitch 56 is mounted on one end of a horizontal tube which extends longitudinally of the base 10. This tube slides through stationary guides 58. A coil compression spring 59 within the tube 57 acts on one end of a slide rod 60 mounted Within the tube. A laterally projecting arm 61 fixed on the rod 60 extends through a slot 62 in the tube and carries an adjustable stop 63 on its extending end. This stop is located for contact by a moving portion of the cross bar 49 of the clamp device 33. A fitting 64 secured on the tube 62 projects laterally through a longitudinal slot 65 provided on a panel of the base 10. A friction clamping handwheel 66 is connected to the fitting 64 and acts to clamp the fitting and the tube 62 in longitudinally adjusted position with respect to the base 10. A vertical index rod 67 travels longitudinally with the tube 62 and fitting 64 and cooperates with several stationary refer ence scales 68 mounted on the panel of the base 10. From this description it will be understood that when the tube 62 is clamped near the right-hand end of the slot 65, maximum travel of the clamp device 33 is permitted before the contact element 63 is engaged to move the rod 60 against the spring 59 and thus actuate the microswitch 56. This microswitch 56 is electrically connected to solenoid valves which control the entrance and egress of hydraulic fluid to the power cylinder assemblies 54.

A clinometer device, generally designated 70, is frictionally attached to the conduit 24 by means .of the releasable clamp chain 71 and rotary knob 72. A circular dial 73 is mounted to turn on the support plate 74 and is clamped in adjusted position by means of the clamping lever 75. A free-swinging pendulum 76 supported from the axis of the dial 73 carries a pointer 77. When the clinometer 70 is attached to the conduit 74, as shown in the drawings, any bending of the pipe is reflected by a change in relative position of the pointer 77 with respect to the dial 73. Each quadrant of the dial is preferably calibrated in different size angular increments. In ordinary use, only one quadrant is used at a time.

In operation, the conduit 24 is moved axially through the clamp devices 33 and 32 and over the blocks 25 and 26. The clinometer 70 is clamped to its extending end. The upper jaws 46 and 36 of the clamp devices are adjusted for the proper height. The blocks 25 and 26 and the bending shoe 29 are chosen for proper contact with the conduit, and the pins 17 and 20 are placed at the proper height for cooperation with the blocks. The extending end of the conduit 24 is positioned at the proper location with respect to the centerline of the bending shoe 29, depending upon the particular bend to be made. The stationary clamp device 32 is then hydraulically actuated to hold the conduit stationary with respect to the frame or base 10. The power cylinder assembly 27 is then hydraulically energized to depress the shoe 29 to put the initial bend in the conduit 24. Hydraulic pressure is maintained on the shoe 29 until the pointer 77 on the clinometer 70 moves relative to the dial 73 to the desired angular extent. It will be observed that this bending action causes the extending end of the conduit 24 to lift upward with respect to the base 10, the pin 20 lifting free of the support surfaces 22.

The'handwheel 66 is then moved longitudinally with respectto the frame slot 65 to the proper position, as indicated by the reference scale 68, to place the stop 63 at exactly the desired spacing from the cross bar '49 on the longitudinally movable clamp device 33. This clamp device 33 is then hydraulically actuated to grip the conduit 24 between the jaws46 and 50. The clamp device 32 is then released. The clamp device 33 is then moved axially toward the bending frame assembly 13 by means of the parallel power cylinder assemblies 54. The forward motion of the clamp device 33 and conduit 24 is interrupted when the moving part 49 engages the adjustable stop 63, thereby operating the microswitch 56. This microswitch acts through solenoid valves to hold the cylinders stationary with respect to the stationary pistons 53. The clamp device 32 is then closed and the conduit 24 is in position to receive another incremental bend from the shoe 29. The moving clamp device 33 is open and then returned axially to its initial position. The cycle is repeated until the desired number of incremental bends has been applied at proper spacing to the conduit 24.

The remote control device 78 carried on a flexible cable 79 is provided to enable the operator to open and close the clamp devices 32 and 33, to apply pressure to the bending shoe 29, and to reciprocate the movable clamp device 33. Manually operated switches on this remote control device 78, held in the hands of the operator, enable the operator to fix his attention on the clinometer pointer 76 so that he may de-energize the bending cylinder 27 at the instant that the pointer shows that the proper degree of incremental bend has been applied, allowing for springback. By suitable actuation of the control buttons on the remote control device 78 the operator is enabled to advance the conduit 24 through the bending frame assembly 13 in step-by-step fashion, with the proper degree of bend applied at each step. Suitable electrically operated sequence of valves may be employed so that the movable clamp device 33 returns to its initial position during downward motion of the bending shoe 29, and while the stationary clamp device 32 is in gripping position, thereby reducing overall sequencing time.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth but that my invention is of the full scope of the appended claims.

I claim:

1. In a machine for bending a conduit, the combination of: a base, bending apparatus mounted on the base, means on the base for feeding the conduit by intermittent motion longitudinally toward said bending apparatus, said means including a pair of releasable clamp devices each having jaws shaped to grip the conduit, means securing a first of the clamp devices against longitudinal movement on the base, the second clamp device including upper and lower clamping jaws each mounted to float relative to said base, meansincluding a hydraulic power cylinder assembly for reciprocating the second clamp device longitudinally on the base, and adjustable means for varying the stroke of said second clamp device, whereby a portion of the conduit may be fed longitudinally throughsaid clamp devices and through said bending frame assembly.

2. In a machine for bending a conduit, the combination of: a base, a bending frame assembly pivotally connected to the base, said assembly having means for contacting the conduit to form an incremental bend, means on the base for feeding the conduit by intermittent motion longitudinally toward said bending frame assembly, said means including a pair of releasable clamp devices each having jaws shaped to grip the conduit, means securinga first of the clamp devices against longitudinal movement on the base, the second clamp device including upper and lower clamping jaws each mounted to float relative to said base, means including a hydraulic power cylinder assembly for reciprocating the second clamp device longitudinally on the base, and adjustable means for varying the stroke of said second clamp device, whereby a portion of the conduit may be fed longitudinally through said clamp devices and through said bending frame assembly.

3. In a machine for bending a conduit to produce a bent section of desired length and curvature, the combination of: a base, bending apparatus pivotally attached to the base and adapted to receive the conduit, means on the base for feeding the conduit by intermittent motion longitudinally toward said bending apparatus, said means including a pair of releasable clamp devices, each having relatively movable jaws shaped to grip the conduit, one jaw of one of said clamp devices being fixed to said base,

the jaws of the other clamp device each being movable to float laterally with respect to the base, power-operated means for reciprocating the latter said clamp device longitudinally on the base, and adjustable means for varying the stroke of the latter said clamp device, whereby at least a portion of the conduit may be fed longitudinally through said clamp devices and through said bending frame assembly.

References Cited UNITED STATES PATENTS 9/1964 Hautau 7215O 1/1967 Hautau 72-450 

